The actual cost (AC) is defined as "the realized cost incurred for the work performed on an activity during a specific time period" in the PMBOK glossary (5th edition, p. 527.) Usually the specific time period is the total project to now. Tracking the actual cost is part of earned value management. Actual cost, also known as Actual Cost of Work Performed, AC or ACWP is used in multiple equations used to evaluate the financial status of the project.
- Why Track Actual Costs and Resource Usage on Projects? by Tom Clark on the PM Times site, February 19, 2008.